In order to determine susceptibility to Serpulina hyodysenteriae infection four inbred strains of SPF mice(Balb/cAnN, Balb/J, C57BL/6J and C57BL/6N) were inoculated with a single intragastric dose of 107 to 108colony forming units ( CFU ) Serpulina hyodysenteriae DJ 70 strain ( S.h ). The criteria used to evaluate theinfection were shedding of bacteria, in faeces at 3, 5, and 7 days post-inoculation (d.p.i), CFU per gram ofcecum, cecal macroscopic changes and histopathological lesions at 14 d.p.i. According to the bacteriologicalcounts and the degree of macroscopic changes the C57BL/6J mice strain seemed to be the most susceptible.Globlet cell hyperplasia, mononuclear cell infiltration of lamina propria and inflammatory oedema ofsubmucosa membrane were the most remarkable changes. No correlation between the lesions and the degreeof macroscopic findings was observed. Histopathological changes found in mice were correlated with thosereported previously in this species, but they differed from those found in pigs. However, progressivebacteriological counts and gross changes of cecum appeared to be a good indicators of S.h infection inC57BL/6J mice and this strain may be a useful animal model in order to study the "in vivo" sensibility of S.h to different antibiotics and chemotherapeutic.Facultad de Ciencias Veterinaria
